An electrical connector assembly is known for interconnecting a mother board and daughter card, in which a plurality of signal contact members are arrayed closely spaced in two elongate rows disposed in respective passageways of a housing of dielectric material. The assembly includes a first connector mounted to the mother board along a surface thereof, and a second connector mounted to an edge of the daughter card and matable with the first connector. In each connector a ground bus member is disposed in a central slot between the rows of signal contacts and provides protection against crosstalk that otherwise would degrade the signals transmitted by the closely spaced signal contacts between the mother board and daughter card. In a larger version, the connectors can have a plurality of signal contact arrays along the length, each with a separate ground bus member therebetween. The ground bus members are generally planar metal members adapted to electrically engage each other in an interwoven fashion transversely along their lengths upon connector mating to provide a continuous ground plane through the mated connector assembly, thereby minimizing the width of the connector assembly.
Such matched impedance connectors are disclosed, for example, in U.S. Pat. No. 5,120,232 and are sold by AMP Incorporated under the MICTOR trademark, a mating plug and receptacle pair having Part Nos. 767003 and 767004; a similar connector assembly is disclosed in U.S. Pat. No. 5,199,885. In the first connector the signal terminals include first contact sections along the board-mounting face extending at right angles to free ends adapted to be surface mounted to conductive pads of the mother board, while the ground buses include post sections extending from the board-mounting face to be inserted into throughholes of the board and soldered to ground circuits thereof. The second contact sections are exposed along the connector mating face to become electrically connected to complementary second contact sections of corresponding signal contacts of the second connector. In the second connector, the first contact sections extend outwardly from the card-mounting face to be soldered to conductive pads of the daughter card, while post sections of the ground buses are inserted into the edge surface to become electrically engaged with ground circuits of the card at transverse through-holes spaced inwardly from the edge. In each connector the second contact sections comprise tines of unequal length extending from a body section and defining pairs of cantilever beam spring arms disposed transversely of the contact rows, with edges thereof being bearing surfaces matable with corresponding portions of the associated second contact sections of the other connector providing redundant electrical engagement for signal transmission of assured integrity. In both connectors the signal contacts are retained in the plastic housings by an interference fit in precisely molded passageways, enhanced by low height protuberances of the contact body sections.
In the MICTOR product, the signal contacts are spaced apart a distance of 0,025 inches. The body sections of the signal contacts are essentially planar, formed from sheet metal, and the housing walls between the contacts are only about 0,011 inches thick and must retain the contacts firmly and precisely located, all with severely restrictive tolerances during manufacture. Each ground bus of a thickness of 0.018 inches, with each ground bus and corresponding housing slot therefor having a transverse length of 0.468 inches. To maintain the minimized overall dimensions of the connector, the walls between the innermost side walls of the signal contact passageways and the ground bus slot are only 0.014 inches thick. In the connector, the signal contacts and the ground buses are force fit into the passageways and slot respectively, thus stressing the thin walls.
It is desired to provide a connector having two rows of elongate contact members that has an insulative housing that is simple to mold precisely in an elongated design with closely spaced contact-receiving passageways having thin barrier walls therebetween for closely spaced contacts, for a precisely dimensioned connector that is economical to manufacture and simple to assemble.
It is desired to provide a connector having two rows of elongate signal contact members and a ground bus member therebetween all in an insulative housing of minimized dimensions in a manner reducing the stress on the thin walls while maintaining the precise positioning of the signal contacts and the ground bus in the housing.
It is further desired to provide such a connector with an increased height between the board-mounting face and the mating face, while maintaining the precision in the dimensions of the insulative material during molding.
Additionally, it is desired to provide such a miniature connector that extends for a substantial distance from a first circuit board to which it is mounted, such that together with a complementary mating connector mounted to a second circuit board parallel to the first circuit board, they interconnect a pair of circuit boards that must be spaced apart a substantial distance within an apparatus or a framework, in order for the spacing to provide a clearance for other electrical or electronic components mounted to one or both boards and that have substantial height, and also clearance to enable air flow for dissipation of heat from such components.